Daylight Harvesting and Solar

Renewables are our past and future

Daylight Harvesting and Solar

In April of 2001, it was time. Our building needed a new roof. Our roof was leaking out heat in the winter and letting in heat in the summer, which wasted precious resources and drove up our energy costs. After much planning and scores of meetings, we decided that not only would we replace the leaky roof with a new high-tech roof, we were going to embark on three innovative, eco-friendly projects:

Daylight Harvesting

Solar Electric Power ( Photo-Voltaic )

Solar Thermal

Since all of these projects involved working on the roof, Jake Hesse, a member of our Maintenance department, suggested to the Board of Directors and the Membership, that we undertake the projects all at once. Though at first glance the price tag seemed a little steep, it would be well worth the cost because we would be be less reliant on non-renewable sources of energy that are harmful to the environment. Fortunately, we were also able to take advantage of rebates and tax credits from the state and federal governments which reduced the cost. Construction started on our fancy new roof in early summer of 2002. There was a little noise and dust, but store operations continued as normal. Now the new roof and the other projects are nearly complete – and we are excited to show them off!

Daylight Harvesting

With increasing our energy efficiency as our goal, the members of Rainbow Grocery turned to daylight harvesting. Daylight Harvesting utilizes available daylight to reduce the amount of electrical light used in a room. Using a combination of skylights and an automatic control, electric lights are turned off when there is enough daylight to sufficiently light the store and turned on when the daylight levels are too low. Our daylight harvesting system is made up of many skylights. Each watertight skylight is fitted with a prismatic dome outside of the building and a diffusing lens inside the building which “spreads out” the light. The diffusing lens softens the light and cuts down the heat transference that can affect perishable items in the store.

Solar Electric

In addition to daylight harvesting, another part of the project is the installation of solar electric ( or photovoltaic ) array. Comprised of tiny cells, the solar electric array absorbs energy from the sun and converts it to electricity without pollution. The cells are laid side by side into larger panels – there are 72 of these panels on the roof at Rainbow. Although, we cannot rely solely on the photovoltaic panels for electricity, it still provides a cleaner energy source – and we are not paying PG & E for it!. As solar electric technology progresses, someday we may be able to go “off the grid”…And won’t that be cool.

Solar Thermal

We also use the sun’s energy to heat our water. Large flat boxes with glass covers are installed on the roof with dark colored copper plates and tubes inside. The copper plates absorb the sunlight’s heat causing it to heat the water that flows through the tubes. This solar thermal system provides Rainbow with half of our hot water.

SHARE:

SINCE 1975

Your local, independent grocery store and a worker-owned cooperative, putting ideals of sustainable living into practice.